A prioritised list of invasive alien species to assist the effective implementation of EU legislation

1. Effective prevention and control of invasive species generally relies on a comprehensive, coherent and representative list of species that enables resources to be used optimally. European Union (EU) Regulation 1143/2014 on invasive alien species (IAS) aims to control or eradicate priority species, and to manage pathways to prevent the introduction and establishment of new IAS; it applies to species considered of Union concern and subject to formal risk assessment. So far, 49 species have been listed but the criteria for selecting species for risk assessment have not been disclosed and were probably unsystematic.
2. We developed a simple method to systematically rank invasive alien species according to their maximum potential threat to biodiversity in the EU. We identified 1323 species as potential candidates for listing, and evaluated them against their invasion stages and reported impacts, using information from databases and scientific literature.
3. 900 species fitted the criter...